EMG test is often performed together with another test called nerve conduction study, which measures the conducting function of nerves. NCV study shows loss of nerve conduction in the distal segment (3 to 4 days after injury). According to NCV study, in axonotmesis there is an absence of distal sensory-motor responses.

Electromyography (EMG) is a medical test performed to evaluate and record the electrical activity (electromyogram) produced by skeletal muscles using an instrument called electromyograph. In axonotmesis, EMG changes (2 to 3 weeks after injury) in the denervated muscles include:

1. Fibrillation potentials (FP)

2. Positive sharp waves

People who suffer from neurotmesis often face a poor prognosis. They will more than likely never regain full functionality of the affected nerve, but surgical techniques do give people a better chance at regaining some function. Current research is focused on new ways to regenerate nerves and advance surgical techniques.

In cases of neurapraxia, the function of the nerves are temporarily impaired. However, the prognosis for recovery from neurapraxia is efficient and quick. Recovery begins within two to three weeks after the injury occurs, and it is complete within six to eight weeks. There are instances when function is not completely restored until four months after the instance of injury. The recovery period of neurapraxia is not an entirely ordered process, but the recovery is always complete and fast.

With Seddon's classification of nerve injuries, it is often tough to identify whether a particular nerve injury is neurotmesis, or axonotmesis, which has damage to the nerve fibres but preservation of the nerve trunk. Due to the damage involved in both of these conditions they will both show paralysis of muscles that are supplied by nerves below the site of the lesion, and will have sensory deficits in accordance with the individual nerves that are damaged. The only way to know for sure if a nerve injury is in fact neurotmesis is to allow for the normal progression of nerve regeneration to take place (nerves regenerate at a rate of approximately 2–4 mm/day proximal to the lesion), and if, after that time, there is still profound muscle paralysis and degeneration in these areas, then it is likely to have been a neurotmesis injury.

Neurotmesis is diagnosed through clinical evaluation of symptoms, physical evaluation, and other diagnostic studies. Patients often undergo a series of muscle strength tests, sensory exam which includes feeling the sensation of light touch, pinprick, vibration, and others. Other tests involved with diagnosis of nerve injury are electromyography (EMG) and nerve conduction studies (NCS). These help to distinguish upper from lower motor neuron disorder as well as diagnose primary muscle disease.

According to medical professionals with the Cleveland Clinic, once an athlete suffers from an episode of cervical spinal cord, team physician or athletic trainer first stabilize the head and neck followed by a thorough neurologic inspection. If the injury is deemed severe, injured parties should be taken to a hospital for evaluation. Athletes that suffer from severe episodes of neurapraxia are urged to consult orthopaedic or spinal medical specialists. In mild cases of neurapraxia, the athlete is able to remove themselves from the field of play. However, the athlete is still advised to seek medical consultation.

The diagnosis may be confirmed by an EMG examination in 5 to 7 days. The evidence of denervation will be evident. If there is no nerve conduction 72 hours after the injury, then avulsion is most likely..

The most advanced diagnostic method is MR imaging of the brachial plexus using a high Tesla MRI scanner like 1.5 T or more. MR helps aid in the assessment of the injuries in specific context of site, extent and the nerve roots involved. In addition, assessment of the cervical cord and post traumatic changes in soft tissues may also be visualised.

The site and type of brachial plexus injury determine the prognosis. Avulsion and rupture injuries require timely surgical intervention for any chance of recovery. For milder injuries involving buildup of scar tissue and for neurapraxia, the potential for improvement varies, but there is a fair prognosis for spontaneous recovery, with a 90–100% return of function.

Electrical stimulation can promote nerve regeneration. The frequency of stimulation is an important factor in the success of both quality and quantity of axon regeneration as well as growth of the surrounding myelin and blood vessels that support the axon. Histological analysis and measurement of regeneration showed that low frequency stimulation had a more successful outcome than high frequency stimulation on regeneration of damaged sciatic nerves.

Surgery can be done in case a nerve has become cut or otherwise divided. Recovery of a nerve after surgical repair depends mainly on the age of the patient. Young children can recover close-to-normal nerve function. In contrast, a patient over 60 years old with a cut nerve in the hand would expect to recover only protective sensation, that is, the ability to distinguish hot/cold or sharp/dull. Many other factors also affect nerve recovery. The use of autologous nerve grafting procedures that involve redirection of regenerative donor nerve fibers into the graft conduit has been successful in restoring target muscle function. Localized delivery of soluble neurotrophic factors may help promote the rate of axon regeneration observed within these graft conduits.

An expanding area of nerve regeneration research deals with the development of scaffolding and bio-conduits. Scaffolding developed from biomaterial would be useful in nerve regeneration if they successfully exhibit essentially the same role as the endoneurial tubes and Schwann cell do in guiding regrowing axons.

Nerve injury is injury to nervous tissue. There is no single classification system that can describe all the many variations of nerve injury. In 1941, Seddon introduced a classification of nerve injuries based on three main types of nerve fiber injury and whether there is continuity of the nerve. Usually, however, (peripheral) nerve injury is classified in five stages, based on the extent of damage to both the nerve and the surrounding connective tissue, since supporting glial cells may be involved. Unlike in the central nervous system, neuroregeneration in the peripheral nervous system is possible. The processes that occur in peripheral regeneration can be divided into the following major events: Wallerian degeneration, axon regeneration/growth, and nerve reinnervation. The events that occur in peripheral regeneration occur with respect to the axis of the nerve injury. The proximal stump refers to the end of the injured neuron that is still attached to the neuron cell body; it is the part that regenerates. The distal stump refers to the end of the injured neuron that is still attached to the end of the axon; it is the part of the neuron that will degenerate but that remains in the area toward which the regenerating axon grows. The study of peripheral nerve injury began during the American Civil War and has greatly expanded to the point of using growth-promoting molecules.